Radiation detectors for scanning systems, and related scanning systems

ABSTRACT

A radiation scanning system comprises a radiation detection sub-assembly, and a routing sub-assembly coupled to the radiation detection sub-assembly. The radiation detection sub-assembly comprises a first substrate electrically connected to the radiation detection sub-assembly, and a second substrate electrically connected to the first substrate. The radiation scanning system further comprises one or more radiation shields between the first substrate and the second substrate, and one or more semiconductor dice electrically connected to the second substrate on a side of the second substrate opposite the first substrate. Related radiation detector arrays radiation scanning systems are also disclosed.

FIELD

Embodiments of the disclosure relate generally to radiation detectorsfor scanning systems. More particularly, embodiments of the disclosurerelate to a radiation system including one or more radiation detectorarrays, the radiation detector arrays individually including one or moreradiation shields between substrates of a routing sub-assembly, and torelated scanning systems.

BACKGROUND

Radiation imaging modalities such as computed tomography (CT) systems,single-photon emission computed tomography (SPECT) systems, digitalprojection systems, line-scan systems, and/or positron emissiontomography (PET), for example, are useful to provide information, orimages, of interior aspects of an object under examination. Intransmission imaging modalities, such as CT, the object is exposed toradiation comprising photons (e.g., such as x-rays, gamma rays, withoutlimitation), and an image(s) is formed based upon the radiation absorbedand/or attenuated by the interior aspects of the object, or rather anumber of radiation photons that are able to pass through the object.Generally, highly dense aspects of the object absorb and/or attenuatemore radiation than less dense aspects, and thus an aspect having ahigher density, such as a bone or metal, for example, will be apparentwhen surrounded by less dense aspects, such as muscle or clothing.Emission imaging modalities such as SPECT and PET form image(s) based onthe radiation emitted from a radioactive tracer that provides functionalinformation of an object.

Radiation systems generally comprise one or more radiation sources(e.g., an x-ray source, gamma-ray source) and a detector array. Thedetector array comprises, among other things, a radiation detectionsub-assembly and an electronic sub-assembly. Radiation photons that passthrough an object impinge a surface of one or more detector elements(also referred to as “detector cells”) of the radiation detectionsub-assembly. The one or more detector elements typically directly orindirectly generate electrical charge in response to the impingingradiation photons.

The detector array typically comprises a plurality of detector elements,respectively configured to convert detected radiation into electricsignals. A magnitude of attenuation by an object in an examinationregion is inversely related to an amount or rate of electrical chargegenerated by a detector element. Based upon the number of radiationphotons detected by respective detector elements and/or the electricalcharge generated by respective detector elements between samplings,images can be reconstructed that are indicative of the density,z-effective (also referred to as the effective atomic number), shape,and/or other properties of the object and/or aspects thereof. Theelectronics sub-assembly is configured to readout electrical charge thathas accumulated within the radiation detector sub-assembly and/ordigitize an analog signal generated from the readout. While theradiation detection sub-assembly converts most of the radiationimpingement thereon into electrical charge, a small percentage of theradiation that impinges the radiation detection sub-assembly traversesthe radiation detection sub-assembly and is incident upon theelectronics sub-assembly. However, the interaction of radiation with theelectronics sub-assembly may damage the electronics sub-assembly and/orshorten a lifespan off electronics disposed therein, for example.

SUMMARY

In accordance with some embodiments of the disclosure, a radiationscanning system comprises a radiation detection sub-assembly, and arouting sub-assembly coupled to the radiation detection sub-assembly.The radiation detection sub-assembly comprises a first substrateelectrically connected to the radiation detection sub-assembly, and asecond substrate electrically connected to the first substrate. Theradiation scanning system further comprises one or more radiationshields between the first substrate and the second substrate, and one ormore semiconductor dice electrically connected to the second substrateon a side of the second substrate opposite the first substrate.

In accordance with other embodiments of the disclosure, a detector arrayfor a radiation system comprises a first substrate coupled to aradiation detection sub-assembly, a second substrate verticallyunderlying the first substrate, conductive structures between the firstsubstrate and the second substrate and electrically connecting the firstsubstrate and the second substrate, and one or more radiation shieldswithin one or more cavities between the first substrate and the secondsubstrate.

In accordance with additional embodiments of the disclosure, a radiationscanning system comprises a radiation detection sub-assembly comprisinga scintillator array, and a photodiode array coupled to the scintillatorarray. The radiation scanning system further comprises a routingsub-assembly comprising a first substrate coupled to the photodiodearray with first conductive structures, the first substrate comprising aprotrusion extending in a direction opposite the photodiode array, asecond substrate coupled to the first substrate with second conductivestructures, and one or more radiation shields between the firstsubstrate and the second substrate, the one or more radiation shieldslaterally spaced from the protrusion. The radiation scanning systemfurther comprises an electronics sub-assembly comprising one or moresemiconductor dice coupled to the second substrate with third conductivestructures, and a connector configured to electrically couple to adetector module.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic of a scanning system to perform transmissionradiation-based scanning, in accordance with embodiments of thedisclosure;

FIG. 2A is a simplified partial cross-sectional view of a detector tile,in accordance with embodiments of the disclosure;

FIG. 2B is a simplified perspective view of a first substrate of thedetector tile of FIG. 2A;

FIG. 2C is a simplified planar view of the detector tile of FIG. 2A;

FIG. 2D is another simplified perspective view of the first substrate ofthe detector tile;

FIG. 2E is a simplified perspective view of view of a second substrateof the detector tile of FIG. 2A;

FIG. 2F is an exploded perspective view of the detector tile;

FIG. 3A is a simplified flow diagram illustrating a method of formingthe detector tile of FIG. 2A, in accordance with embodiments of thedisclosure;

FIG. 3B through FIG. 3E are simplified perspective views illustrating amethod of forming the detector tile of FIG. 2A, in accordance withembodiments of the disclosure;

FIG. 4A and FIG. 4B are a respective simplified perspective view and asimplified planar view of another detector tile, in accordance withadditional embodiments of the disclosure;

FIG. 5A and FIG. 5B are a respective simplified cross-sectional view anda planar view of a detector tile, in accordance with other embodimentsof the disclosure;

FIG. 6A and FIG. 6B are a respective simplified cross-sectional view anda planar view of an additional detector tile, in accordance withadditional embodiments of the disclosure;

FIG. 7 is a simplified partial cross-sectional view of a detector tile,in accordance with embodiments of the disclosure;

FIG. 8 is a simplified partial cross-sectional view of another detectortile, in accordance with other embodiments of the disclosure; and

FIG. 9A and FIG. 9B are simplified partial cross-sectional view ofapplication specific integrated circuit (ASIC) packages, in accordancewith embodiments of the disclosure.

DETAILED DESCRIPTION

The illustrations presented in this disclosure are not meant to beactual views of any particular scanning system for performingradiation-based (e.g., computed tomography (CT)) scanning or componentthereof or component thereof, but are merely idealized representationsemployed to describe illustrative embodiments. Thus, the drawings arenot necessarily to scale.

The following description provides specific details, such as materialtypes, dimensions, and processing conditions in order to provide athorough description of embodiments of the disclosure. However, a personof ordinary skill in the art will understand that the embodiments of thedisclosure may be practiced without employing these specific details.Indeed, the embodiments of the disclosure may be practiced inconjunction with conventional fabrication techniques employed in theindustry. In addition, the description provided below does not form acomplete apparatus or system for a scanning system including a detectorarray comprising detector elements. Only those process acts andstructures necessary to understand the embodiments of the disclosure aredescribed in detail below. Also note, any drawings accompanying thepresent application are for illustrative purposes only, and are thus notdrawn to scale. Additionally, elements common between figures may retainthe same numerical designation.

Drawings presented herein are for illustrative purposes only, and arenot meant to be actual views of any particular material, component,structure, device, or system. Variations from the shapes depicted in thedrawings as a result, for example, of manufacturing techniques and/ortolerances, are to be expected. Thus, embodiments described herein arenot to be construed as being limited to the particular shapes or regionsas illustrated, but include deviations in shapes that result, forexample, from manufacturing. For example, a region illustrated ordescribed as box-shaped may have rough and/or nonlinear features, and aregion illustrated or described as round may include some rough and/orlinear features. Moreover, sharp angles that are illustrated may berounded, and vice versa. Thus, the regions illustrated in the figuresare schematic in nature, and their shapes are not intended to illustratethe precise shape of a region and do not limit the scope of the presentclaims. The drawings are not necessarily to scale. Additionally,elements common between figures may retain the same numericaldesignation.

As used herein, the term “configured” refers to a size, shape, materialcomposition, orientation, and arrangement of one or more of at least onestructure and at least one apparatus facilitating operation of one ormore of the structure and the apparatus in a predetermined way.

As used herein, the terms “vertical,” “longitudinal,” “horizontal,” and“lateral” are in reference to a major plane of a structure and are notnecessarily defined by Earth's gravitational field. A “horizontal” or“lateral” direction is a direction that is substantially parallel to themajor plane of the structure, while a “vertical” or “longitudinal”direction is a direction that is substantially perpendicular to themajor plane of the structure. The major plane of the structure isdefined by a surface of the structure having a relatively large areacompared to other surfaces of the structure. With reference to thefigures, a “horizontal” or “lateral” direction may be perpendicular toan indicated “Z” axis, and may be parallel to an indicated “X” axisand/or parallel to an indicated “Y” axis; and a “vertical” or“longitudinal” direction may be parallel to an indicated “Z” axis, maybe perpendicular to an indicated “X” axis, and may be perpendicular toan indicated “Y” axis.

As used herein, features (e.g., regions, structures, devices) describedas “neighboring” one another means and includes features of thedisclosed identity (or identities) that are located most proximate(e.g., closest to) one another. Additional features (e.g., additionalregions, additional structures, additional devices) not matching thedisclosed identity (or identities) of the “neighboring” features may bedisposed between the “neighboring” features. Put another way, the“neighboring” features may be positioned directly adjacent one another,such that no other feature intervenes between the “neighboring”features; or the “neighboring” features may be positioned indirectlyadjacent one another, such that at least one feature having an identityother than that associated with at least one the “neighboring” featuresis positioned between the “neighboring” features. Accordingly, featuresdescribed as “vertically neighboring” one another means and includesfeatures of the disclosed identity (or identities) that are located mostvertically proximate (e.g., vertically closest to) one another.Moreover, features described as “horizontally neighboring” one anothermeans and includes features of the disclosed identity (or identities)that are located most horizontally proximate (e.g., horizontally closestto) one another.

As used herein, spatially relative terms, such as “beneath,” “below,”“lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,”“right,” and the like, may be used for ease of description to describeone element's or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. Unless otherwise specified,the spatially relative terms are intended to encompass differentorientations of the materials in addition to the orientation depicted inthe figures. For example, if materials in the figures are inverted,elements described as “below” or “beneath” or “under” or “on bottom of”other elements or features would then be oriented “above” or “on top of”the other elements or features. Thus, the term “below” can encompassboth an orientation of above and below, depending on the context inwhich the term is used, which will be evident to one of ordinary skillin the art. The materials may be otherwise oriented (e.g., rotated 90degrees, inverted, flipped, etc.) and the spatially relative descriptorsused herein interpreted accordingly.

As used herein, the term “substantially” in reference to a givenparameter, property, or condition means and includes to a degree thatone of ordinary skill in the art would understand that the givenparameter, property, or condition is met with a degree of variance, suchas within acceptable tolerances. By way of example, depending on theparticular parameter, property, or condition that is substantially met,the parameter, property, or condition may be at least 90.0 percent met,at least 95.0 percent met, at least 99.0 percent met, at least 99.9percent met, or even 100.0 percent met.

As used herein, “about” or “approximately” in reference to a numericalvalue for a particular parameter is inclusive of the numerical value anda degree of variance from the numerical value that one of ordinary skillin the art would understand is within acceptable tolerances for theparticular parameter. For example, “about” or “approximately” inreference to a numerical value may include additional numerical valueswithin a range of from 90.0 percent to 110.0 percent of the numericalvalue, such as within a range of from 95.0 percent to 105.0 percent ofthe numerical value, within a range of from 97.5 percent to 102.5percent of the numerical value, within a range of from 99.0 percent to101.0 percent of the numerical value, within a range of from 99.5percent to 100.5 percent of the numerical value, or within a range offrom 99.9 percent to 100.1 percent of the numerical value.

Terms used in the present disclosure and especially in the appendedclaims (e.g., bodies of the appended claims) are generally intended as“open” terms (e.g., the term “including” should be interpreted as“including, but not limited to,” the term “having” should be interpretedas “having at least,” the term “includes” should be interpreted as“includes, but is not limited to,” etc.). As used herein, “each” meanssome or a totality. As used herein, “each and every” means a totality.

Additionally, if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, means at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” or “one or more of A, B, and C, etc.” isused, in general such a construction is intended to include A alone, Balone, C alone, A and B together, A and C together, B and C together, orA, B, and C together, etc.

Further, any disjunctive word or phrase presenting two or morealternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” should be understood to include the possibilities of “A”or “B” or “A and B.”

In this description the term “coupled” and derivatives thereof may beused to indicate that two elements co-operate or interact with eachother. When an element is described as being “coupled” to anotherelement, then the elements may be in direct physical or electricalcontact or there may be intervening elements or layers present. Incontrast, when an element is described as being “directly coupled” toanother element, then there are no intervening elements or layerspresent. The terms “on” and “connected” may be used in this descriptioninterchangeably with the term “coupled,” and have the same meaningunless expressly indicated otherwise or the context would indicateotherwise to a person having ordinary skill in the art.

According to embodiments disclosed herein, a radiation scanning systemis configured to inspect translated objects using radiation-basedscanning. More specifically, disclosed are embodiments of radiationdetector arrays, each comprising a radiation detection sub-assembly, anelectronics sub-assembly, and a routing sub-assembly between theradiation detection sub-assembly and the electronics sub-assembly. Therouting sub-assembly includes a first substrate electrically connectedto a second substrate and one or more radiation shields between thefirst substrate and the second substrate, the one or more radiationshields configured to shield (e.g., block) an amount of radiationpassing therethrough, and attenuate impingent radiation to reduce anamount of radiation passing therethrough to one or more components ofthe electronics sub-assembly. In other words, the one or more radiationshields may at least partially protect one or more components of theelectronics sub-assembly from impingent radiation. The first substrateand the second substrate include electrical connections and electricalrouting for routing electronic signals from the radiation detectionsub-assembly through the routing sub-assembly and to the electronicssub-assembly. The routing sub-assembly may facilitate formation of thecomponents of the electronics sub-assembly in a package assembly (asopposed to as a bare semiconductor die). The size and shape of the firstsubstrate and the second substrate facilitates an increased thickness ofthe one or more radiation shields and a density of electricalinterconnects between the first substrate and the second substrate.

FIG. 1 is a schematic of a scanning system 100 to perform transmissionradiation-based (e.g., CT) scanning, in accordance with embodiments ofthe disclosure. Techniques in accordance with this disclosure may findapplicability with, for example, CT systems, diffraction systems, and/orother systems comprising other radiation imaging modalities and otherradiation detector systems. For example, the scanning system 100 may beuseful with line-scan systems, digital projection systems, diffractionsystems, and other systems configured to detect radiation.

The scanning system 100 may be configured to examine one or more objects102 (e.g., a human subject, a series of suitcases at an airport,freight, parcels, without limitation). The scanning system 100 mayinclude, for example, a stator 104 and a rotor 106 rotatable relative tothe stator 104. During examination, the object(s) 102 may be located ona support 108, such as, for example, a bed, roller conveyor, or conveyorbelt, that is selectively positioned in an examination region 110 (e.g.,a hollow bore in the rotor 106 in which the object(s) 102 is exposed toradiation 112), and the rotor 106 may be rotated about the object(s) 102by a motivator 115 (e.g., motor, drive shaft, chain, withoutlimitation).

The rotor 106 may surround a portion of the examination region 110 andmay be configured as, for example, a gantry supporting at least oneradiation source 114 (e.g., an ionizing x-ray source, gamma-ray source,without limitation), the at least one radiation source 114 oriented toemit the radiation 112 toward the examination region 110 and at leastone radiation detector 116 supported on a substantially diametricallyopposite side of the examination region 110 (which may also be asubstantially diametrically opposite side of rotor 106) relative to theradiation source(s) 114. During a contemplated examination of object(s)102 by the scanning system 100, the radiation source(s) 114 emits fanand/or cone shaped radiation 112 configurations toward the examinationregion 110. The radiation 112 may be emitted, for example, at leastsubstantially continuously or intermittently (e.g., a pulse of radiation112 followed by a resting period during which the radiation source(s)114 is not activated).

As the emitted radiation 112 traverses the examination region 110 andthe object(s) 102, the radiation 112 may be attenuated differently bydifferent aspects of the object(s) 102. Because different aspectsattenuate different amounts (e.g., percentages, without limitation) ofthe radiation 112, an image or images can be generated based upon theattenuation, or variations in the number of radiation photons that aredetected by the radiation detector 116. As non-limiting examples, moredense aspects of the object(s) 102, such as an inorganic material, mayattenuate more of the radiation 112 than less dense aspects, such asorganic materials, causing fewer photons to be detected by the radiationdetector 116. As another non-limiting example, more dense regions of theobject(s) 102, such as bone or a metal plate may attenuate more of theradiation 112 than less dense aspects, such as skin or clothing, causingfewer photons to be detected by the radiation detector 116.

The radiation detector 116 may include, for example, many individualdetector tiles arranged in a pattern (e.g., a row or an array) on one ormore detection assemblies (also referred to as detection modules,detector modules, and/or the like), which are operatively connected toone another to form the radiation detector 116, which may comprise aso-called detector measurement system (DMS). Each detector tile mayinclude one or more arrays of detectors elements arranged in a pattern(e.g., rows and columns). In some embodiments, the detector elements maybe configured to indirectly convert (e.g., using a scintillator arrayand photodetectors) detected radiation into analog signals. In otherembodiments, the detector elements are configured to directly convertthe detected radiation into analog signals. Further, the radiationdetector 116, or detection assemblies thereof, may include electroniccircuitry, such as, for example, an analog-to-digital (A/D) converter,configured to filter the analog signals, digitize the analog signals,and/or otherwise process the analog signals and/or digital signalsgenerated thereby. Digital signals output from the electronic circuitrymay be conveyed from the radiation detector 116 to digital processingcomponents configured to store data associated with the digital signalsand/or further process the digital signals.

In some embodiments, the digital signals may be transmitted to an imagegenerator 118 configured to generate image space data, also referred toas images, from the digital signals using a suitable analytical,iterative, and/or other reconstruction technique (e.g., backprojectionreconstruction, tomosynthesis reconstruction, iterative reconstruction,without limitation). In this way, the data may be converted fromprojection space to image space, a domain that may be moreunderstandable by a user 120 viewing the image(s), as a non-limitingexample. Such image space data may depict a two dimensionalrepresentation of the object(s) 102 and/or a three dimensionalrepresentation of the object(s) 102. In other embodiments, the digitalsignals may be transmitted to other digital processing components, suchas a threat analysis component 121, for processing and, optionally,generation of an alert or augmentation of such image space data withadditional information for the user (e.g., with indications of adetected threat or areas of interest, without limitation) in response tosuch processing.

The illustrated scanning system 100 may also include a terminal 122(e.g., a workstation or other computing device), configured to receivethe image(s), which can be displayed on a monitor 124 to the user 120(e.g., security personnel, medical personnel, without limitation). Inthis way, the user 120 can inspect the image(s) to identify areas ofinterest within the object(s) 102. The terminal 122 may also beconfigured to receive user input which may direct operations of thescanning system 100 (e.g., a rate at which the support 108 moves,activation of the radiation source(s) 114, without limitation) andconnected to additional terminals 122 through a network connection(e.g., a local area network or the Internet, without limitation).

A control system 126 may be coupled (e.g., operably coupled) to theterminal 122. The control system 126 may be configured to automaticallycontrol at least some operations of the scanning system 100. Forexample, the control system 126 may be configured to directly and/orindirectly, automatically, and dynamically control the rate at which thesupport 108 moves through the examination region 110, the rate at whichthe rotor 106 rotates relative to the stator 104, activation,deactivation, and output level of (e.g., intensity of radiation emittedby) the radiation source(s) 114, or any combination or subcombination ofthese and/or other operating parameters. In some embodiments, thecontrol system 126 may also accept manual override instructions from theterminal 122 and issue instructions to the scanning system 100 to alterthe operating parameters of the scanning system 100 based on the manualoverride instructions. The control system 126 may be located proximateto a remainder of the scanning system 100 (e.g., integrated into thesame housing or within the same room as the remaining components) or maybe distal from the scanning system 100 (e.g., located in another room,such as, for example, an on-site control room, an off-site serverlocation, a cloud storage system). The control system 126 may bededicated to control a single scanning system 100, or may controlmultiple scanning systems 100 in an operative grouping or subgrouping.

FIG. 2A is a simplified partial cross-sectional view in the XZ plane ofa detector tile 200 (also referred to as a “radiation detector tile”),in accordance with embodiments of the disclosure. The detector tile 200may comprise a portion of the radiation detector 116 (FIG. 1 ) of thescanning system 100 (FIG. 1 ). The detector tile 200 comprises aradiation detection sub-assembly 210, an electronics sub-assembly 280,and a routing sub-assembly 220 vertically between the radiationdetection sub-assembly 210 and the electronics sub-assembly 280. Therouting sub-assembly 220 may be vertically between the radiationdetection sub-assembly 210 and the electronics sub-assembly 280. Therouting sub-assembly 220 may be configured to route (e.g., convey)signals (e.g., low-level analog signals) between the radiation detectionsub-assembly 210 and the electronics sub-assembly 280. The electronicssub-assembly 280 comprises one or more elements configured to processthe signals (e.g., convert the analog signals to digital signals, filterthe analog signals and/or digital signals respectively routed by therouting sub-assembly) from the radiation detection sub-assembly 210.

The radiation detection sub-assembly 210 comprises one or more detectorelements (as depicted in FIG. 2A, a respective one of such detectorelements includes a respective scintillator 202 and a portion of thephotodetector array 206 vertically adjacent and coupled to thescintillator 202) and configured to detect radiation and/or generateanalog signals indicative of detected radiation. In some embodiments,the radiation detection sub-assembly 210 is configured to convertdetected radiation into analog signals. In some embodiments, theradiation detection sub-assembly 210 is configured to indirectly convertthe radiation into electrical charge and comprises a scintillator array205 and a photodetector array 206 (e.g., a photodiode array) directlyvertically neighboring and contacting the scintillator array 205. Thescintillator array 205 may be located in a radiation pathway 201 betweenthe photodetector array 206 and the radiation source 114 (FIG. 1 ).

In other embodiments, rather than the scintillator array 205 and thephotodiode array 206, the radiation detection sub-assembly 210 comprisesa direct conversion material configured to directly convert radiationinto electrical charge. The direct conversion material may comprise,among other things, cadmium zinc telluride (CZT), cadmium telluride(CdTe), or other materials configured to directly convert radiationphotons, such as x-ray photons or gamma photons into electrical charge.

With continued reference to FIG. 2A, the scintillator array 205comprises a plurality of scintillators 202 a, 202 b, 202 c, 202 d, 202e, 202 f, 202 g, 202 h (collectively referred to as scintillators 202)configured to convert radiation photons impingent thereon intoluminescent photons (e.g., in the visible or infrared wavelengthspectrum). The scintillators 202 may correspond to a detector element(detector cell) of the detector tile 200. In some embodiments,neighboring scintillators 202 of the scintillator array 205 are spacedfrom each other by a gap (such a gap depicted in FIG. 2A as the spacehaving the light-reflective material 204 therein).

Although FIG. 2A illustrates that the scintillator array 205 includeseight (8) scintillators 202, the disclosure is not so limited. In otherembodiments, the scintillator array 205 comprises more than eight (8)scintillators 202, such as greater than or equal to sixteen (16)scintillators 202, greater than or equal to thirty-two (32)scintillators 202, greater than or equal to sixty-four (64)scintillators 202, greater than or equal to one hundred twenty-eight(128) scintillators 202, greater than or equal to two hundred fifty-six(256) scintillators 202, greater than or equal to five hundred twelve(512) scintillators 202, greater than or equal to one thousandtwenty-four (1024) scintillators 202, or greater than or equal to twothousand forty-eight (2048) scintillators 202. In some embodiments, thescintillator array 205 comprises one thousand twenty-four (1024)scintillators 202. In some embodiments, the scintillator array 205comprises two separate scintillator arrays 205, each comprising, forexample five hundred twelve (512) scintillators 202 (e.g., two 16×32scintillator arrays 205). In other embodiments, the scintillator array205 comprises any desired number of arrays to generate a desired totalnumber of scintillators 202.

The scintillators 202 may individually be formed of and includegadolinium oxysulfide (GOS), cadmium tungstate (CdWO₄, CWO), bismuthgermanate (BGO) (B₁₄Ge₃O₁₂), cesium iodide (CsI), sodium iodide (NaI),lutetium orthosilicate (LSO) (Lu₂SiO₅, Lu₄O₁₂Si₃, H₁₂Lu₄O₁₂Si₃), or anamorphous material. In some embodiments, the scintillators 202 areindividually formed of and include GOS.

In some embodiments, at least a portion of the gap between horizontallyneighboring (e.g., in the X-direction, in the Y-direction) scintillators202 of the scintillator array 205 may be filled with a light-reflectivematerial 204 configured to reduce cross-talk between horizontallyneighboring scintillators 202. The light-reflective material 204 may bedisposed vertically (e.g., in the Z-direction) above the scintillators202 and configured to reflect the radiation (e.g., light) verticallydownwards in a direction of the photodetector array 206. Thelight-reflective material 204 may substantially surround thescintillators 202. In some embodiments, each scintillator 202 issurrounded by the light-reflective material on each horizontal (e.g., inthe X-direction, in the Y-direction) side thereof and on a vertically(e.g., in the Z-direction) upper direction thereof. In some embodiments,a vertically lower surface of the scintillators 202 is contacted by thephotodetector array 206. Accordingly, in some embodiments, thelight-reflective material 204 surrounds first horizontal sides, secondhorizontal sides, and upper surfaces of each scintillator 202.

The photodetector array 206 comprises a plurality of photodetectors. Thephotodetectors may include back-illuminated photodiodes,front-illuminated photodiodes, or a combination thereof. Thephotodetectors may be configured to detect luminescent photons impingingthereon, may be configured to generate electrical charge responsive todetecting the luminescent photons, or both. The electrical charge may beperiodically sampled (e.g., measured) to generate an analog signal,which is provided to the electronics sub-assembly 280 via the routingsub-assembly 220. Accordingly, the photodetectors of the photodetectorarray 206 are configured to generate an analog signal indicative of thenumber of luminescent photons detected by the photodetector betweensamplings (e.g., which corresponds to and correlates to the amount ofradiation detected between samplings within a region of the scintillatorarray 205 proximate and corresponding to the sampled photodetector).

The photodetector array 206 includes bond pads 208 on a vertically(e.g., in the Z-direction) lower side thereof. In some embodiments, thebond pads 208 may be arranged on the lower side of the photodetectorarray 206 to correspond to the number and arrangement of photodetectorsof the photodetector array 206. Stated another way, in some embodiments,each photodetector of the photodetector array 206 may independently beassociated with one of the bond pads 208.

With continued reference to FIG. 2A, the routing sub-assembly 220includes a first substrate 230 including bond pads 209 on an uppersurface 232 thereof. The radiation detection sub-assembly 210 is coupledto the routing sub-assembly 220 by way of a first interconnection layer250 comprising an electrically conductive adhesive (ECA) 254, such as anelectrically conductive epoxy, electrically connecting the bond pads 208of the photodetector array 206 to the bond pads 209 of the firstsubstrate 230. The bond pads 209 on the first substrate 230 maycorrespond (e.g., in number and positioning) to the bond pads 208 of thephotodiode array 206. The first interconnection layer 250 is configuredto convey electrical signals from the radiation detection sub-assembly210 (e.g., from the photodetector array 206) through the routingsub-assembly 220 to the electronics sub-assembly 280.

Although the first interconnection layer 250 has been described andillustrated as comprising the electrically conductive adhesive 254coupling bond pads 208 of the photodiode array 206 to the bond pads 209of the first substrate 230, the disclosure is not so limited. In otherembodiments, the first interconnection layer 250 may include conductivestructures (e.g., conductive balls, conductive bumps) electricallyconnected to the conductive pads of the photodetector array 206, andadditional conductive pads on an upper surface of the routingsub-assembly 220. Accordingly, in some embodiments, the firstinterconnection layer 250 includes one or more of bond pads, solderballs, conductive epoxy, electrically conductive spring contacts, orother structures configured to form physical and electrical contactbetween the radiation detection sub-assembly 210 and the routingsub-assembly 220.

The bond pads 208 and the bond pads 209 may individually be formed ofand include conductive material, such as, for example, one or more of ametal (e.g., tungsten, titanium, nickel, platinum, rhodium, ruthenium,aluminum, copper, molybdenum, iridium, silver, gold), and a metal alloy.In some embodiments the bond pads 208 and the bond pads 209 individuallycomprise tungsten. In other embodiments, the bond pads 208 comprisecopper. However, the disclosure is not so limited and the bond pads 208and the bond pads 209 may individually comprise conductive materialsother than those described.

The routing sub-assembly 220 is located vertically (e.g., in theZ-direction) below the radiation detection sub-assembly 210 and thefirst interconnection layer 250. In some embodiments, the radiationdetection sub-assembly 210 is located between the radiation pathway 201and the routing sub-assembly 220 such that radiation passes through theradiation detection sub-assembly 210 (a majority of which is convertedto electrical signals) prior to passing through the routing sub-assembly220.

The routing sub-assembly 220 comprises the first substrate 230 (alsoreferred to as a “top substrate” or an “upper substrate”), a secondsubstrate 240 (also referred to as a “bottom substrate” or a “lowersubstrate”) in electrical communication with the first substrate 230,and one or more radiation shields 245 between the first substrate 230and the second substrate 240.

FIG. 2B is a simplified partial perspective view of the first substrate230 and FIG. 2C is a simplified partial planar view of the detector tile200 illustrating various components thereof, in accordance withembodiments of the disclosure. To more clearly illustrate components ofthe first substrate 230, the first substrate 230 is vertically invertedin FIG. 2B with respect to the orientation of the first substrate 230 inFIG. 2A. In FIG. 2C, although different components may not be located inthe same vertical plane (e.g., in the XY plane), they are illustrated inFIG. 2C to illustrate the relative position and orientation of thecomponents of the detector tile 200.

With combined reference to FIG. 2A through FIG. 2C, the first substrate230 comprises a substantially planar upper surface 232 in contact withand coupled to the first interconnection layer 250 and a lower surface233 including and partially defining a protruding portion 234 (alsoreferred to as a “raised portion”) extending towards the secondsubstrate 240 such that surfaces of the first substrate 230 and surfacesof the second substrate 240 define one or more cavities 242 in which theradiation shields 245 are disposed.

With reference to FIG. 2B and FIG. 2C, in some embodiments, theprotruding portion 234 exhibits a cross-shape. In other embodiments, theprotruding portion 234 exhibits another shape, such as a square shapewith one or more square-shaped openings in the middle thereof, arectangular shape with one or more rectangular-shaped openings in themiddle thereof. However, the disclosure is not so limited and the shapeof the protruding portion 234 may be different than those described.

With continued reference FIG. 2C, in some embodiments, the protrudingportion 234 may include a first portion 234A extending in a firsthorizontal direction (e.g., in the Y-direction) and a second portion234B extending in a second horizontal direction (e.g., the X-direction)and intersecting the first portion 234A, such as proximate a horizontalcenter of the first substrate 230. In some embodiments, a horizontaldimension D₁ of the first portion 234A may be larger than a horizontaldimension D₂ of the second portion 234B. In other embodiments, thehorizontal dimension D₁ of the first portion 234A is substantially thesame as the horizontal dimension D₂ of the second portion 234B.

In some embodiments, sidewalls 236 of the protruding portion 234 defineat least a portion of the cavities 242. In some embodiments, each cavity242 is partially defined by the sidewalls 236 of the protruding portion234, the lower surface 233 of the first substrate 230 and an uppersurface 244 of the second substrate 240. In some embodiments, two of thelateral sides defining each cavity 242 comprise the sidewall of 236 ofthe protruding portion 234, and other lateral sides (e.g., two otherlateral sides) defining the cavity 242 are open. In some suchembodiments, and with reference to FIG. 2A, at least some of the lateralsides of the radiation shields 245 may be exposed and the cavities 242may be referred to as “open cavities.”

A vertical (e.g., in the Z-direction) height H of the protruding portion234 may be defined by the sidewalls 236 and may be within a range offrom about 0.30 millimeter (mm) to about 2.0 mm, such as from about 0.75mm to about 1.0 mm, from about 1.0 mm to about 1.5 mm, or from about 1.5mm to about 2.0 mm. In some embodiments, the height H is from about 0.75mm to about 1.0 mm. However, the disclosure is not so limited, and theheight H may be different than those described. The vertical height H ofthe protruding portion 234 may correspond to a distance between thelower surface 233 of the first substrate 230 in contact with theradiation shield 245 and the lower surface 233 of the protruding portion234 in contact with a second interconnection layer 260 electricallycoupling the first substrate 230 to the second substrate 240.

Each cavity 242 may be sized and shaped to receive one radiation shield245. In some embodiments, the first substrate 230 defines four (4)cavities 242 and the radiation detection sub-assembly 210 is configuredto include four (4) radiation shields 245. In other embodiments, and asdescribed in further detail below, each cavity 242 may be sized andshaped to house more than one radiation shield 245.

In some embodiments, the radiation shields 245 are in contact with thelower surface 233 of the first substrate 230. The radiation shields 245may be horizontally spaced from the sidewalls 236 of the protrudingportion 234. In other embodiments, the radiation shields 245 directlycontact the sidewalls 236 of the protruding portion 234. Although theradiation shields 245 have been described and illustrated as contactingsurfaces of the first substrate 230, the disclosure is not so limited.In other embodiments, the radiation shields 245 contact one or moresurfaces of the second substrate 240. In some embodiments, the radiationshields 245 contact surfaces of the first substrate 230 and surfaces ofthe second substrate 240.

The radiation shields 245 may be configured (e.g., shaped to, include aspecific material or multiple materials) to inhibit a passage ofradiation (e.g., x-ray radiation, gamma-ray radiation) therethroughand/or attenuate (e.g., absorb) radiation impingent thereon. Theradiation shields 245 may be formed of and include one or morematerials, the materials comprising one or more of tungsten, lead,tantalum, leaded glass, and heavy metal powder composites (e.g.,tungsten powder in a polymer binder). In some embodiments, some or atotality of radiation shields 245 comprise tungsten, lead, tantalum,leaded glass, and heavy metal powder composites. In some embodiments,one or more of (e.g., all of) the radiation shields 245 comprisetungsten.

A thickness T₁ of the radiation shields 245 may be less than or equal tothe height H of the protruding portion 234. In some embodiments, thethickness T₁ is less than the height H of the protruding portion 234. Insome such embodiments, a vertically lower surface of the radiationshield 245 may be located vertically above the lower surface 233 of thefirst substrate 230 in contact with the second interconnection layer 260(e.g., located closer to the first interconnection layer 250).

The thickness T₁ of the radiation shield 245 may be tailored at leastpartially based on the power of the radiation 112 (FIG. 1 ), thesensitivity of electronic components of the detector tile 200 toradiation, or both. For example, the thickness T₁ may be increased forrelatively higher radiation 112 sources and for detector tiles 200including more sensitive electronic components. The thickness T₁ may bewithin a range of from about 0.75 mm to about 2.0 mm, such as from about0.75 mm to about 1.0 mm, from about 1.0 mm to about 1.5 mm, or fromabout 1.5 mm to about 2.0 mm. In some embodiments, the thickness T₁ isabout 1.0 mm. However, the disclosure is not so limited and thethickness T₁ may be different than those described. In some embodiments,the radiation shields 245 may be stacked in the vertical direction(e.g., the Z-direction). For example, in some embodiments, a firstradiation shield 245 may be in contact with the lower surface 233 of thefirst substrate 230 and a second radiation shield 245 may be verticallybelow (e.g., the Z-direction) and within the same lateral boundaries(e.g., in the X-direction, in the Y-direction) as the first radiationshield 245 and may be located on the upper surface 244 of the secondsubstrate 240. In some such embodiments, the first shield and the secondshield may exhibit the same thickness.

A gap G may separate a lowermost surface of the radiation shield 245from the upper surface 244 of the second substrate 240. Stated anotherway, in some embodiments, the radiation shield 245 is vertically spacedfrom the second substrate 240 by the gap G. The size of the gap G may bebased on the sum of the difference between the height H and thethickness T₁ and the vertical height of the second interconnection layer260.

The first substrate 230 may be formed of and include one or more of anorganic polymer (e.g., a plastic material), a ceramic material (e.g.,aluminum oxide), fiberglass, silicon, silicon dioxide, sapphire,germanium, gallium arsenide, a printed circuit board material (e.g.,laminates, resin impregnated B-stage cloth), glass reinforced epoxylaminates, FR4 grade materials (e.g., glass epoxy), or other suitablematerials.

The second interconnection layer 260 electrically coupling the firstsubstrate 230 to the second substrate 240 may comprise bond pads 263 onthe bottom surface 233 of the first substrate 230, first conductivestructures 262 coupled to the bond pads 263, and bond pads 264 coupledto the upper surface 244 of the second substrate 240. The bond pads 263may facilitate electrical connection between the first substrate 230first conductive structures 262 and the bond pads 264 may facilitateelectrical connection between the first conductive structures 262 andthe second substrate 240. The bond pads 263 of the first substrate 230may be located on the bottom surface 233 of the first substrate 230 onthe protruding portion 234. The first conductive structures 262 may beformed of and include one or more of the materials described above withreference to the first conductive pads 208. The bond pads 263 and thebond pads 264 may be substantially similar to the bond pads 208 and maybe formed of and include one or more of the materials described abovewith reference to the conductive pads 208.

With collective reference to FIG. 2A through FIG. 2C, the firstconductive structures 262 may be located on protruding portion 234 ofthe first substrate 230. In some embodiments, the second portion 234Bincludes a greater number of the first conductive structures 262 thanthe first portion 234A.

Although the second interconnection layer 260 has been described andillustrated as including the first conductive structures 262, the bondpads 263, and the bond pads 264, the disclosure is not so limited. Inother embodiments, the second interconnection layer 260 comprises one ormore of solder balls, conductive epoxy, electrically conductive springcontacts, or other structures configured to form physical and electricalcontact between the radiation first substrate 230 and the secondsubstrate 240. In addition, although FIG. 2A through FIG. 2C have beenillustrated as including a particular number of bond pads 263, firstconductive structures 262, and bond pads 264 of the secondinterconnection layer 260, the disclosure is not so limited. The numberof bond pads 263, first conductive structures 262, and bond pads 264 maycorrespond to a number of photodiodes of the photodetector array 206. Insome embodiments, the number of bond pads 263, first conductivestructures 262, and bond pads 264 may be greater than about 1,000 (e.g.,1,024).

With continued reference to FIG. 2A, first routing structures 238 may beformed within the first substrate 230 and configured to electricallyconnect the first interconnection layer 220 to the secondinterconnection layer 260. The first routing structures 238 electricallyconnect, for example, the bond pads 209 of the first interconnectionlayer 220 to the bond pads 263 of the second interconnection layer 260.In some embodiments, each first routing structure 238 may individuallycouple one of the bond pads 209 to one of the bond pads 263. The firstrouting structures 238 may convey, for example, low level analog signalsfrom the radiation detection sub-assembly 210 through the firstsubstrate 230 and to the second substrate 240 for conveying the signalsto the electronics sub-assembly 280. The first routing structures 238may facilitate routing of the electrical signals through the firstsubstrate 230 and around the radiation shields 245. In some embodiments,the first routing structures 238 are external to and laterally offsetfrom the radiation shields 245 and route around the radiation shields245. In some embodiments, the first routing structures 238 extend intothe protruding portion 234 of the first substrate 230. For clarity andease of understanding the description, FIG. 2A illustrates only onefirst routing structure 238 through the first substrate 230. It will beunderstood that several first routing structures 238 (e.g.,corresponding to a number of the first conductive pads 208) extendthrough the first substrate 230.

The first routing structures 238 may be formed of and include conductivematerial, such as one or more of tungsten, molybdenum, nickel, gold,copper, tin, and silver. In some embodiments, such as where the firstsubstrate 230 comprises a ceramic material, the first routing structures238 comprise one tungsten and/or molybdenum and may be plated withnickel and/or gold (e.g., the first routing structures 238 may be platedat locations proximate the bond pads 209 and the bond pads 263. In otherembodiment, such as where the first substrate 230 comprises a printedcircuit board, the first routing structures 238 may be formed of andinclude copper. In some such embodiments, the first routing structures238 may be plated with one or more of nickel, gold, tin, and silver atlocations proximate the bond pads 209 and the bond pads 263.

The second substrate 240 may include second routing structures 246 toelectrically couple the second interconnection layer 260 to a thirdinterconnection layer 270 comprising second conductive structures 272between bond pads 273 and bond pads 275. The second routing structures246 may comprise a conductive material, such as one or more of thematerials described above with reference to the first routing structures238. In some embodiments, the second routing structures 246 comprise thesame material composition as the first routing structures 238. In someembodiments, each of the second routing structures 246 may individuallyelectrically connect a bond pad 264 of the second interconnection layer260 to a bond pad 273 of the third interconnection layer 270. In someembodiments, a number of the second routing structures 246 maycorrespond to a number of the bond pads 263 and a number of the bondpads 273. For clarity and ease of understanding the description, FIG. 2Aillustrates only one second routing structure 246. It will be understoodthat several second routing structures 246 (e.g., corresponding to anumber of the bond pads 263) extend through the second substrate 240.

The second substrate 240 may be formed of and include one or more of thematerials described above with reference to the first substrate 230. Insome embodiments, the second substrate 240 comprises substantially thesame material composition as the first substrate 230. In otherembodiments, the second substrate 240 comprises a different materialcomposition than the first substrate 230. In some embodiments, one ofthe first substrate 230 or the second substrate 240 comprises a ceramicmaterial and the other of the first substrate 230 or the secondsubstrate 240 comprises an FR4 material (e.g., glass epoxy). In someembodiments, the first substrate 230 comprises a ceramic material andthe second substrate 240 comprises another material, such as an FR4material.

The third interconnection layer 270 electrically couples the secondsubstrate 240 to the electronics sub-assembly 280. The electronicssub-assembly 280 is configured to process analog signals generated bythe radiation detection sub-assembly 210 to generate digital signals. Byway of non-limiting example, the electronics sub-assembly 280 maycomprise analog-to-digital (A/D) converters, digital-to-analogconverters, photon counters, or other electronic components. In someembodiments, the electronics sub-assembly 280 comprises one or moreapplication specific integrated circuit (ASIC) packages 282. The ASICpackages 282 may be configured to, among other things, filter the analogsignals (e.g., to reduce noise, smooth the signal, enhance aspects ofthe signal), cover the analog signals to digital signals, and filter thedigital signals. In some embodiments, each ASIC package 282 comprises anA/D converter chip. In other embodiments, the electronics sub-assemblycomprises a bare die, and/or a bare die on substrate (e.g., a carriersubstrate).

In some embodiments, a number of the ASIC packages 282 may be equal tothe number of the radiation shields 245. In some embodiments, thedetector tile 200 includes four ASIC packages 282.

Each ASIC package 282 may individually include, for example, one or moresemiconductor dice 286. Each semiconductor die 286 may comprise, forexample, a silicon wafer or silicon substrate including one or morecontrol logic devices for effectuating operation of the detector tile200. By way of non-limiting example, the semiconductor dice 286 may beconfigured to filter the analog signals (e.g., to reduce noise, smooththe signal, enhance aspects of the signal) from the radiation detectionsub-assembly 210, cover the analog signals to digital signals, andfilter the digital signals.

In some embodiments, each ASIC package 282 comprises two (2) of thesemiconductor dice 286. However, the disclosure is not so limited and inother embodiments, the ASIC packages 282 individually include fewer(e.g., one (1)) semiconductor die 286, or more semiconductor dice 286,such as more than two (2) semiconductor dice 286, more than three (3)semiconductor dice 286, or more than four (4) semiconductor dice 286.

The semiconductor dice 286 may be separated from one another by, forexample, a dielectric material 288. The dielectric material 288 mayinclude, for example, silicon dioxide, phosphosilicate glass (PSG),borophosphosilicate glass (BPSG), or another material.

The semiconductor dice 286 may be surrounded (e.g., encapsulated) by apackage material 289. The package material 289 may comprise, forexample, a plastic material, such as a thermoplastic material, a metalmaterial (e.g., a nickel-cobalt ferrous alloy, such as KOVAR® of CRSHoldings, Inc. of Delaware), or a ceramic material.

The ASIC packages 282 may be electrically connected to a connector 290by means of third routing structures 284 extending through the secondsubstrate 240. The third routing structures 284 electrically connect thebond pads 273 to bond pads 291 connected to third conductive structures292 connected to the connector 290. Third routing structures 293 may beelectrically coupled to the third conductive structures 292 andconfigured to route one or more signals to and/or from the connector290. The connector 290 may be operably coupled to, for example,connection cables of a detector module of the radiation detector 116 ofthe scanning system 100 of FIG. 1 . Power may be provided to detectortile 200 through the connector 290. The third routing structures 284 maybe formed of and include conductive material, such as one or more of thematerials described above with reference to the first routing structures238. In some embodiments, the third routing structures 284 comprisesubstantially the same material composition as the first routingstructures 238. The bond pads 291 may be formed of and include one ormore conductive materials, such as one or more of the materialsdescribed above with reference to the bond pads 208. The third routingstructures 293 may be formed of and include conductive material, such asone or more of brass, bronze, copper, and steel. In some embodiments,the third routing structures 293 are plated with another metal, such asone or more of tin, silver, gold, and nickel.

With continued reference to FIG. 2B, in some embodiments, thesemiconductor dice 286 are located vertically (e.g., in the Z-direction)below the radiation shields 245 and are located within lateralboundaries defined by the radiation shields 245. In other words, thesemiconductor dice 286 may not laterally extend beyond lateralboundaries of the radiation shields 245 directly vertically overlyingthe semiconductor dice 286. Placing the semiconductor dice 286 withinlateral boundaries defined by the radiation shields 245 may physicallyprotect (e.g., block) radiation that would otherwise be impingent uponthe semiconductor dice 286 and may, therefore, protect the semiconductordice 286 from undesired damage from the radiation.

Although the radiation shields 245 have been described and illustratedas having a larger lateral cross-sectional area (e.g., in the XY plane)than the semiconductor dice 286, the disclosure is not so limited. Inother embodiments, the radiation shields 245 have substantially the samecross-sectional area (e.g., lateral footprint) as the semiconductor dice286. In some such embodiments, one or more (e.g., all of) lateral edgesof the semiconductor dice 286 may be laterally aligned with one or more(e.g., all of) lateral edges of the radiation shields 245.

Although the semiconductor dice 286 have been described and illustratedas being located within the ASIC packages 282, the disclosure is not solimited. In other embodiments, the electronics sub-assembly 280 does notinclude the ASIC packages 282 and the semiconductor dice 286 aredirectly flip chip bonded to a lower surface 248 of the second substrate240.

FIG. 2D is a simplified partial schematic perspective view of the uppersurface 244 of the second substrate 240. FIG. 2E is a simplified partialperspective view of the lower surface 248 of the second substrate 240.With collective reference to FIG. 2A and FIG. 2D, the upper surface 244of the second substrate 240 comprises a pattern 265 of the bond pads 264corresponding to the pattern of the first conductive structures 262 onthe protruding portion 234 of the first substrate 230. Regions of theupper surface 244 corresponding to locations of the cavities 242 (FIG.2A, FIG. 2B) and the radiation shields 245 may not include the bond pads263.

With reference to FIG. 2E, the lower surface 248 of the second substrate240 may include the second conductive structures 272 of the thirdinterconnection layer 270. In some embodiments, the lower surface 248includes bond pads 295 for electrically connecting the second substrate240 to the connector 290 (FIG. 2A), such as by soldering pins of theconnector 290 thereto.

FIG. 2F is a simplified exploded view of the detector tile 200illustrating the components thereof in a disassembled state. Thedetector tile 200 includes the scintillator array 205 including, forexample, a first scintillator array 205 a and a second scintillatorarray 205 b neighboring the first scintillator array 205 a; thephotodetector array 206 underlying the scintillator array 205 andincluding, for example, a first photodiode array 206 a and a secondphotodiode array 206 b; the routing sub-assembly 220 underlying thephotodetector array 206, the routing sub-assembly 220 including thefirst substrate 230 vertically underlying the photodetector array 206,the radiation shields 245 vertically underlying the first substrate 230and between the first substrate 230 and the second substrate 240; andthe ASIC packages 282 coupled to an underside of the second substrate240.

FIG. 3A through FIG. 3E illustrate a method of forming the detector tile200, in accordance with embodiments of the disclosure. FIG. 3A is asimplified flow chart illustrating a method of forming the radiationdetector. FIG. 3B through FIG. 3E are simplified perspective viewsillustrating different acts of forming the radiation detector.

With reference to FIG. 3A, the method 300 includes act 302 includingbonding one or more radiation shields to a first substrate to form astructure; act 304 including connecting the structure to a secondsubstrate to form a routing sub-assembly; act 306 including attachingone or more semiconductor dice to the routing sub-assembly; and act 308including attaching a radiation detection sub-assembly to the routingsub-assembly to form a radiation detector.

Act 302 includes bonding one or more radiation shields to a firstsubstrate to form a structure. For example, with reference to FIG. 3B,one or more radiation shields 245 may be attached to the first substrate230 (e.g., to lower surfaces 233 (FIG. 2A) of the first substrate 230)to form a structure 310. In FIG. 3B, the radiation shields 245 areillustrated above the first substrate 230, but it will be understoodthat the radiation shields 245 are physically brought into contact withthe lower surface 233 of the first substrate 230 and bonded to the firstsubstrate 230.

In some embodiments, the radiation shields 245 are bonded to the firstsubstrate 230 with an electrically conductive adhesive (ECA). By way ofnon-limiting example, the radiation shields 245 may be attached to thefirst substrate with one or more electrically conductive epoxies. Insome embodiments, the radiation shields 245 are individually connectedto an electrical ground of the first substrate 230. Electricallyconnecting the radiation shields 245 to ground may reduce cross talk andnoise during operation of the detector tile 200 (FIG. 2A).

With reference again to FIG. 3A, act 304 includes connecting thestructure 310 (FIG. 3B) to a second substrate to form a routingsub-assembly. Referring to FIG. 3C, the structure 310 (FIG. 3B) isconnected to the second substrate 240 to form a routing sub-assembly320. In some embodiments, the second substrate 240 is attached to thestructure 310 by attaching the first conductive structures 262 (FIG. 2A)to the bond pads 264 (FIG. 2A) with a solder paste and performing areflow soldering process to form the second interconnection layer 260(FIG. 2A) and electrically connect the second substrate 240 to the firstsubstrate 230.

Referring back to FIG. 3A, act 306 includes attaching one or moresemiconductor dice to the routing sub-assembly. With reference to FIG.3D, one or more ASIC packages 282 (each including one or moresemiconductor dice) may be attached to the lower surface 248 of thesecond substrate 240 of the routing sub-assembly 320 to form a structure330. By way of non-limiting example, bond pads 273 of the secondsubstrate 240 may be connected to the second conductive structures 272with a solder paste to form the third interconnection layer 270 (FIG.2A) and electrically connect the ASIC packages 282 to the secondsubstrate 240.

Act 308 includes attaching a radiation detection sub-assembly to therouting sub-assembly to form a radiation detector. With reference toFIG. 3E, a radiation detection sub-assembly 340 including thephotodetector array 206 and the scintillator array 205 is attached tothe routing sub-assembly 330 to form a radiation detector 350. In someembodiments, the radiation detection sub-assembly 340 is attached to theupper surface 232 of the first substrate 230. By way of non-limitingexample, an electrically conductive adhesive 254 (FIG. 2A) may be usedto electrically connect the bond pads 209 of the first substrate 230 tothe bond pads 208 of the photodetector array 206.

Although the detector tile 200 of FIG. 2A through FIG. 2F has beendescribed and illustrated as including the radiation shields 245individually within an open cavity 242 (FIG. 2A) wherein at least somelateral sides of the radiation shields 245 are exposed (e.g., notneighboring the protruding portion 234 of the first substrate 230), thedisclosure is not so limited. In other embodiments, the first substrate230 defines enclosed cavities.

FIG. 4A is a simplified perspective view of a first substrate 430, inaccordance with embodiments of the disclosure. FIG. 4B is a simplifiedtop-down view of the first substrate 430. The view of the firstsubstrate 430 in FIG. 4B is similar to the view of the first substrate230 of FIG. 2C. The first substrate 430 may replace the first substrate230 (FIG. 2A) of the detector tile 200. With combined reference to FIG.4A and FIG. 4B, the first substrate 430 may include a bottom surface 433(corresponding to the lower surface 233 (FIG. 2A) of the first substrate230 (FIG. 2A)).

With reference to FIG. 4A, the bottom surface 433 may define cavities442. The cavities may be defined by sidewalls 436. The sidewalls 436 maysubstantially surround all sides of each cavity 442. With reference toFIG. 4B, surfaces of the cavities 442 are illustrated in broken lines443. Each cavity 442 may be configured to house one radiation shield245. One or more semiconductor dice 286 (FIG. 2A) may be located withinlateral boundaries and vertically under each radiation shield 245, asdescribed above with reference to FIG. 2A through FIG. 2F.

Conductive structures 462 (corresponding to the first conductivestructures 262 (FIG. 2A)) may be located on the bottom surface 433 ofthe first substrate 430. In some embodiments, the conductive structures462 may be substantially the same as the first conductive structures262. In some embodiments, the conductive structures 462 are located onthe bottom surface 433 proximate only some lateral sides of each cavity442. For example, only the bottom surface 433 proximate inner lateralsides (e.g., lateral sides of the each cavity 442 proximate a lateralcenter of the second substrate 430) of each cavity 442 are neighbored bythe conductive structures 462 in some embodiments. In some suchembodiments, the bottom surface 433 of outer lateral sides of eachcavity 442 (e.g., lateral sides of the second substrate 430 locatedaround a periphery of the second substrate 430) do not includeconductive structures 462.

In other embodiments, the outer lateral sides of each cavity 442includes the conductive structures 462, as illustrated by conductivestructures 462 shown in broken lines around a periphery of the secondsubstrate 430.

FIG. 5A is a simplified partial cross-sectional view in the XZ plane ofa detector tile 500, in accordance with embodiments of the disclosure.The detector tile 500 may be substantially similar to the detector tile200 described above with reference to FIG. 2A through FIG. 2F, exceptthe detector tile 500 may include a single cavity 542 and a differentnumber of radiation shields 545 and ASIC packages 582 than the detectortile 200. Components and structures of the detector tile 500 that arethe same or substantially the same as corresponding components andstructures of the detector tile 200 retain the same numericaldesignation. FIG. 5B is a simplified top-down view of the detector tile500 illustrating the same view of the detector tile 200 as thatillustrated in FIG. 2C.

With reference to FIG. 5A and FIG. 5B, the detector tile 500 includes arouting sub-assembly 520 including a first substrate 530 attached to andin electrical communication with a second substrate 540. The firstsubstrate 530 may be substantially the same as the first substrate 230(FIG. 2B), except that the first substrate 530 includes protrudingportions 534 around a periphery thereof to define a single cavity 542.The second substrate 540 may be substantially similar to the secondsubstrate 240 (FIG. 2B), except the location of the bond pads 264 andthe first conductive structures 262 may be different to correspond tothe location of the bond pads 263 (corresponding to the location ofradiation shields 545). A radiation shield 545 may be disposed withinthe cavity 542 and configured to vertically overlie the ASIC package582. The radiation shield 545 may be formed of and include substantiallythe same materials described above with reference to the radiationshield 245 described above with reference to FIG. 2A through FIG. 2F. Insome embodiments, the radiation shield 545 comprises tungsten. Thecavity 542 is illustrated in broken lines in FIG. 5B.

With reference to FIG. 5A, an upper surface 532 of the first substrate530 is in contact with the photodetector array 206 by means of the firstinterconnection layer 250, which is substantially the same as the firstinterconnection layer 250 described above with reference to FIG. 2A. Alower surface 533 of the first substrate 530 may include bond pads 263in electrical communication with the first conductive structures 262,which are in turn, in electrical communication with the bond pads 264 toform the second interconnection layer 260. Since the protruding portions534 are located proximate a periphery of the first substrate 530, thefirst conductive structures 262, the bond pads 263, and the bond pads264 of the second interconnection layer 260 are located around theperiphery of the first substrate 530 (e.g., vertically underlying theprotruding portions 534).

With continued reference to FIG. 5A, the lower surface 248 of the secondsubstrate 240 may be in electrical communication with the ASIC package582 by means of the third interconnection layer 270. The thirdinterconnection layer 270 may be located vertically below and withinlateral boundaries of the radiation shields 545. In some embodiments,the third interconnection layer 270 is located at a laterally centralportion of the detector tile 500.

The ASIC package 582 may vertically underlie and be located withinlateral boundaries of the radiation shield 545. The ASIC package 582 maybe substantially similar to the ASIC packages 582 described above withreference to FIG. 2B, except that the ASIC package 582 may include morethan one semiconductor die 286. For example, the ASIC package 582 mayinclude four (4) semiconductor dice 286.

FIG. 6A is a simplified partial cross-sectional view of a detector tile600, in accordance with embodiments of the disclosure. The detector tile600 may be substantially the same as the detector tile 500 of FIG. 5Aand FIG. 5B, except that the detector tile 600 includes a routingsub-assembly 620 including a first substrate 630 including more than onecavity 642 (illustrated in broken lines in FIG. 6B) defined by sidewalls636 of protruding portions 634, the cavities 642 located within alaterally central portion of the detector tile 600. The first substrate630 is in electrical communication with a second substrate 640 by meansof the second interconnection layer 260. A radiation shield 645 may bedisposed within each cavity 642. The radiation shield 645 may be formedof and include substantially the same materials described above withreference to the radiation shield 245. FIG. 6B is a simplified planarview of the detector tile 600 illustrating the same view as thatillustrated in FIG. 2C.

With collective reference to FIG. 6A and FIG. 6B, the secondinterconnection layer 260 includes the first conductive structures 262,the bond pads 263, and the bond pads 264 laterally between the radiationshields 645 below a protruding portion 634 of the first substrate 630.Stated another way, the second interconnection layer 260 may includefirst conductive structures 262, the bond pads 263, and the bond pads264 outside lateral boundaries of the radiation shields 645 andlaterally between (e.g., in the X-direction) a first radiation shield645 and a second radiation shield 645. In some embodiments, the firstconductive structures 262, the bond pads 263, and the bond pads 264 maybe located around a periphery of the first substrate 630 and the secondsubstrate 640 and in a laterally central portion of the first substrate630 and the second substrate 640 laterally between the cavities 642. Thesecond substrate 640 may be substantially similar to the secondsubstrate 540, except the pattern of the bond pads 264 and the firstconductive structures 262 may correspond to the pattern of the bond pads263 of the first substrate 630.

Although the radiation detector tiles 200 (FIG. 2A, FIG. 2C), 500 (FIG.5A, FIG. 5B), 600 (FIG. 6A, FIG. 6B) have been described and illustratedas comprising the respective first substrate 230 (FIG. 2A, FIG. 2C), 530(FIG. 5A, FIG. 5B), 630 (FIG. 6A, FIG. 6B) including sidewalls 236 (FIG.2A, FIG. 2C), 536 (FIG. 5A, FIG. 5B), 636 (FIG. 6A, FIG. 6B) definingthe respective protruding portions 234 (FIG. 2A, FIG. 2C), 534 (FIG. 5A,FIG. 5B), 634 (FIG. 6A, FIG. 6B), the disclosure is not so limited. Inother embodiments, the second substrate may include protruding portions.In some such embodiments, the first substrate 230, 530, 630 may includeprotruding portions 234, 534, 634 or may not include the protrudingportions 234, 534, 634.

FIG. 7 is a simplified partial cross-sectional view of a detector tile700, in accordance with embodiments of the disclosure. The detector tile700 is substantially similar to the detector tile 200 described abovewith reference to FIG. 2A through FIG. 2F, except the detector tile 700includes a routing sub-assembly 720 including a first substrate 730electrically connected to a second substrate 740, the second substrate740 including a protruding portion 734.

The first substrate 730 may include an upper surface 732 and a lowersurface 733, each of the upper surface 732 and the lower surface 733being substantially planar and extending substantially parallel witheach other. The first substrate 730 is coupled to the second substrate740 by the second interconnection layer 260.

The second substrate 740 includes the protruding portion 734. Theprotruding portion 734 includes sidewalls 737 defining cavities 742between the first substrate 730 and the second substrate 740. Radiationshields 745 may be disposed between the first substrate 730 and thesecond substrate 740 within the cavities 742, as described above withreference to the radiation shields 245 (FIG. 2B). The radiation shields745 may be substantially the same as the radiation shields 245 (FIG.2A).

In other embodiments, each of the first substrate and the secondsubstrate may include a protruding portion to define one or morecavities. FIG. 8 is a simplified partial cross-sectional view of adetector tile 800, in accordance with embodiments of the disclosure. Thedetector tile 800 includes a routing sub-assembly 820 including a firstsubstrate 830 including a protruding portion 834 electrically connectedto a second substrate 840, the second substrate 840 including anadditional protruding portion 835.

The first substrate 830 may include an upper surface 832 and a lowersurface 833. The upper surface 832 may be substantially planar, asdescribed above with reference to the upper surface 732 (FIG. 7 ). Thelower surface 833 may at least partially define the protruding portion834 and cavities 842 between the first substrate 830 and the secondsubstrate 840. At least portions of the cavities 842 are defined bysidewalls 836 of the protruding portion 834 and sidewalls 837 of theadditional protruding portion 835. The first substrate 830 is coupled tothe second substrate 840 by the second interconnection layer 860.

As illustrated in FIG. 8 , in some embodiments, the secondinterconnection layer 260 may be located within vertical boundariesdefined by the radiation shields 845.

The second substrate 840 includes the additional protruding portion 835.The additional protruding portion 835 includes sidewalls 837 at leastpartially defining the cavities 842 between the first substrate 830 andthe second substrate 840. Radiation shields 845 may be disposed betweenthe first substrate 830 and the second substrate 840 within the cavities842.

Although the ASIC packages 282 (FIG. 2A, FIG. 2C, FIG. 6A, FIG. 6B, FIG.7 , FIG. 8 ), 582 (FIG. 5A, FIG. 5B) have been described and illustratedas having a particular configuration, such as a particular number ofsemiconductor dice 286 and the dielectric material 288, the disclosureis not so limited. FIG. 9A is a simplified partial cross-sectional viewof an ASIC package 900, in accordance with embodiments of thedisclosure. The ASIC package 900 may replace any of the ASIC packages282, 582 of the detector tiles 200 (FIG. 2B), 500 (FIG. 5A), 600 (FIG.6A), 700 (FIG. 7 ), 800 (FIG. 8 ) described herein. The ASIC package 900may include a single semiconductor die 286 disposed within the packagematerial 289.

FIG. 9B is a simplified partial cross-sectional view of an ASIC package910, in accordance with embodiments of the disclosure. The ASIC package900 may replace any of the ASIC packages 282, 582 of the detector tiles200 (FIG. 2B), 500 (FIG. 5A), 600 (FIG. 6A), 700 (FIG. 7 ), 800 (FIG. 8) described herein. The ASIC package 910 may include two semiconductordice 286 disposed within the package material 289. In some embodiments,the semiconductor dice 286 are vertically aligned with each other.

Any of the detector tiles 200 (FIG. 2B), 500 (FIG. 5A), 600 (FIG. 6A),700 (FIG. 7 ), 800 (FIG. 8 ) may include ASIC packages including onesemiconductor die 286 as described above with reference to FIG. 9A andthe ASIC package 900, two semiconductor dice 286 as described above withreference to the ASIC packages 282 (FIG. 2A) and 910 (FIG. 9B), or foursemiconductor dice 286, as described above with reference to the ASICpackage 582 (FIG. 5A, FIG. 6A, FIG. 7 , FIG. 8 ).

Accordingly, in some embodiments the radiation detector tiles 200 (FIG.2A, FIG. 2C), 500 (FIG. 5A, FIG. 5B), 600 (FIG. 6A, FIG. 6B), 700 (FIG.7 ), 800 (FIG. 8 ) may include one or more ASIC packages 282 (FIG. 2A,FIG. 2C, FIG. 6A, FIG. 6B, FIG. 7 , FIG. 8 ), 582 (FIG. 5A, FIG. 5B),900 (FIG. 9A), 910 (FIG. 9B). In some embodiments, the detector tiles200, 500, 600, 700, 800 include four ASIC packages. In otherembodiments, the detector tiles 200, 500, 600, 700, 800 include agreater number of ASIC packages, such as more than four (4) ASICpackages, more than five (5) ASIC packages, or more than six (6) ASICpackages.

In some embodiments, the radiation detector tiles 200 (FIG. 2A, FIG.2C), 500 (FIG. 5A, FIG. 5B), 600 (FIG. 6A, FIG. 6B), 700 (FIG. 7 ), 800(FIG. 8 ) include different number of radiation shields 245 (FIG. 2A,FIG. 4B), 545 (FIG. 5A, FIG. 5B), 645 (FIG. 6A, FIG. 6B), 745 (FIG. 7 ),845 (FIG. 8 ) than those illustrated. In some embodiments, the detectortiles 200, 500, 600, 700, 800 include one radiation shield per ASICpackage 282 (FIG. 2A, FIG. 2C, FIG. 6A, FIG. 6B, FIG. 7 , FIG. 8 ), 582(FIG. 5A, FIG. 5B), 900 (FIG. 9A), 910 (FIG. 9B). In other embodiments,the detector tiles 200, 500, 600, 700, 800 may include fewer radiationshields than ASIC packages, such as two radiation shields and four ASICpackages or six ASIC packages.

Accordingly, radiation scanning systems according to embodimentsdescribed herein may include one or more radiation tiles comprising aradiation detection sub-assembly and a routing sub-assembly connected tothe radiation detection sub-assembly and configured to electricallycouple the radiation detection sub-assembly to an electronicssub-assembly. The routing sub-assembly includes a first substratecoupled to the radiation detection sub-assembly and a second substratecoupled to the first substrate and the electronics sub-assembly. One ormore cavities defined by surfaces of the first substrate and the secondsubstrate are located between the first substrate and the secondsubstrate. One or more radiation shields are disposed in the one or morecavities and configured to reduce impingent radiation from damaging thecomponents of the electronics sub-assembly. The size and shape of thefirst substrate and the second substrate facilitate forming theradiation shields between the first substrate and the second substrateand routing electronic circuitry through the first substrate and thesecond substrate.

While embodiments of the disclosure may be susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and have been described indetail herein. However, it should be understood that the disclosure isnot limited to the particular forms disclosed. Rather, the disclosureencompasses all modifications, variations, combinations, andalternatives falling within the scope of the disclosure as defined bythe following appended claims and their legal equivalents.

1. A radiation scanning system, comprising: a radiation detectionsub-assembly; a routing sub-assembly coupled to the radiation detectionsub-assembly, the routing sub-assembly comprising: a first substrateelectrically connected to the radiation detection sub-assembly; and asecond substrate electrically connected to the first substrate; one ormore radiation shields between the first substrate and the secondsubstrate, the one or more radiation shields contacting one of the firstsubstrate and the second substrate and separated from the other of thefirst substrate and the second substrate by an air gap; and one or moresemiconductor dice electrically connected to the second substrate on aside of the second substrate opposite the first substrate.
 2. Theradiation scanning system of claim 1, wherein the first substratecomprises a protrusion defining at least a portion of a bottom surfaceof the first substrate, sidewalls of the protrusion at least partiallydefining one or more cavities in which the one or more radiation shieldsare disposed.
 3. The radiation scanning system of claim 2, wherein aheight of the protrusion is greater than a thickness of the one or moreradiation shields.
 4. The radiation scanning system of claim 1, whereinan upper surface of the second substrate is spaced from a surface of theone or more radiation shields.
 5. The radiation scanning system of claim1, wherein the one or more semiconductor dice are located within lateralboundaries defined by the one or more radiation shields.
 6. Theradiation scanning system of claim 1, wherein the one or more radiationshields comprises four radiation shields.
 7. The radiation scanningsystem of claim 1, wherein: the first substrate comprises one or moreprotrusions around a periphery thereof; and the one or more radiationshields are disposed in one or more cavities defined at least partiallyby the one or more protrusions and an upper surface of the secondsubstrate.
 8. The radiation scanning system of claim 1, wherein theradiation detection sub-assembly comprises a photodiode diode coupled toa scintillator array.
 9. The radiation scanning system of claim 1,wherein the one or more semiconductor dice are disposed within one ormore ASIC packages.
 10. The radiation scanning system of claim 1,wherein the one or more semiconductor dice each individually comprises aflip chip semiconductor die.
 11. A detector array for a radiationsystem, the detector array comprising: a first substrate coupled to aradiation detection sub-assembly; a second substrate verticallyunderlying the first substrate, the first substrate comprising aprotrusion extending between the first substrate and the secondsubstrate; conductive structures between the first substrate and thesecond substrate and electrically connecting the first substrate and thesecond substrate, the conductive structures coupled to the protrusion;and one or more radiation shields within one or more cavities betweenthe first substrate and the second substrate.
 12. The detector array ofclaim 11, wherein the one or more radiation shields are external to thefirst substrate and the second substrate.
 13. The detector array ofclaim 11, wherein the one or more radiation shields are coupled to thefirst substrate with an electrically conductive adhesive.
 14. (canceled)15. The detector array of claim 11, wherein the protrusion exhibits across-shaped horizontal cross-section.
 16. The detector array of claim10, wherein the first substrate comprises a ceramic material.
 17. Aradiation scanning system, comprising: a radiation detectionsub-assembly comprising: a scintillator array; and a photodiode arraycoupled to the scintillator array; a routing sub-assembly comprising: afirst substrate coupled to the photodiode array with first conductivestructures, the first substrate comprising a protrusion extending in adirection opposite the photodiode array; a second substrate coupled tothe first substrate with second conductive structures; and one or moreradiation shields between the first substrate and the second substrate,the one or more radiation shields laterally spaced from the protrusion;and an electronics sub-assembly comprising: one or more semiconductordice coupled to the second substrate with third conductive structures;and a connector configured to electrically couple to a detector module.18. The radiation scanning system of claim 17, wherein the one or moreradiation shields comprise a single radiation shield verticallyoverlying two or more semiconductor dice.
 19. The radiation scanningsystem of claim 17, wherein a lower surface of the one or more radiationshields is closer to an upper surface of the first substrate than alower surface of the protrusion.
 20. The radiation scanning system ofclaim 17, wherein the second substrate comprises an additionalprotrusion extending in a direction opposite the electronicssub-assembly.
 21. The radiation scanning system of claim 20, wherein thesecond conductive structures are directly between the protrusion of thefirst substrate and the additional protrusion of the second substrate.